Share This!

Tuesday, August 23, 2016

Issuing Direct SQL from MVC5

Recently I needed to add a quick updater that added a value to Table1 when someone copied data from Table2.
Now, the normal way to do this with Entity Framework is to load the entity change the value, then save the changed entity.
But I am a SQL guy from way back, and rather than fetch the entire record and write it all back through Entity Framework, I figured it would be way more efficient if I just sent the database an update directly. Turns out that for us old SQL developers, it's terribly easy to do just that.
Here is my example subroutine, for your dining pleasure.
/// <summary>
/// Updates a Toolkit with the number of the Assignment ID Created from it.
/// </summary>
/// <param name="ToolkitID">The toolkit ID to be updated</param>
/// <param name="AssignmentID">The AssignmentID to attach</param>
public static void UpdateToolkitWithAssignmentID(int ToolkitID, int AssignmentID)
{
    using (ORM db = new ORM())
    {
        try
        {
            db.Database.ExecuteSqlCommand(
                "UPDATE [dbo].[ToolkitRequests] SET[AssignmentID] = @AID Where[UniqueId] = @ID",
                new SqlParameter("@AID", AssignmentID),
                new SqlParameter("@ID", ToolkitID)
                );
        }
        finally
        {
            db.Dispose();
        }
    }
}

That's it! It's super fast, and there is no mucking about in Entity Framework. NOTE that all the EF validity checking is skipped when you do this, so use it in cases where it's a simple SQL and you can ensure data integrity yourself. In my case, there is no way to get in this routine without valid values in both params, so I know I won't get surprised with a stray NULL.

Issuing Direct SQL from MVC5

Recently I needed to add a quick updater that added a value to Table1
when someone copied data from Table2.

Now, the normal way to do this with Entity Framework is to load the
Entity, and change the value, then save the changed entity.

But I am a SQL guy from way back, and rather than fetch the entire
record and write it all back through Entity Framework, I figured it
would be Way more efficient if I just sent the database an update
directly. Turns out that for us old SQL developers, it's terribly easy
to do just that.

Here is my example subroutine, for your dining pleasure.


        /// 
        /// Updates a Toolkit with the number of the Assignment ID Created from it. If you are trying to remove an assignment id from a toolkit, use RemoveAssignmentFromToolkit()
        /// 
        /// The toolkit ID to be updated
        /// The AssignmentID to attach
        public static void UpdateToolkitWithAssignmentID(int ToolkitID, int AssignmentID)
        {
            using (ORM db = new ORM())
            {
                try
                {
                    db.Database.ExecuteSqlCommand(
                        "UPDATE [dbo].[ToolkitRequests] SET[AssignmentID] = @AID Where[UniqueId] = @ID",
                        new SqlParameter("@AID", AssignmentID),
                        new SqlParameter("@ID", ToolkitID)
                        );
                }
                finally
                {
                    db.Dispose();
                }
            }
        }









That's it! It's super fast, and there is no mucking about in Entity
Framework. NOTE that all the EF validity checking is skipped when you
do this, so use it in cases where it's a simple SQL and you can ensure
data integrity yourself. In my case, there is no way to get in this
routine without valid values in both params, so I know I won't get
surprised with a stray NULL.


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

Friday, June 3, 2016

MVC - JQuery Prompt User to Save Modified Page.

I had users clicking off my page while doing data entry, and I needed to make sure they didn't forget to save their modifications.

 

Here is a simple example HTML page that implements a rudimentary check.  This is not tested for all data types.   Enjoy.

 

 

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

    <title> Safe Exit Test </title>

    <script src="http://code.jquery.com/jquery-1.11.0.min.js"></script>

</head>

 

<body>

    <form action="">

        <input type="number" name="value" />

        <input type="submit" name="commit" />

    </form>

 

    <a href="http://209software.com">209software</a>

 

    <script>

        $(document).ready(function () {

            formmodified = 0;

            $('form *').change(function () {

                formmodified = 1;

            });

            window.onbeforeunload = confirmExit;

            function confirmExit() {

                if (formmodified == 1) {

                    return "New information not saved. Do you wish to leave the page?";

                }

            }

            $("input[name='commit']").click(function () {

                formmodified = 0;

            });

        });

    </script>

</body>

</html>

 

Thursday, April 21, 2016

MVC: Comparing old values to postback

I wanted to compare a couple values to their previous values on postback (Edit) to do some special processing.


So rather than put hidden fields on the page with the old values, why not just load the record on postback and do my checking there?  Easy peasy!


Assignment oldAssignment = db.Assignments.Find(assignment.UniqueID);

... then I can make my comparisons:
bool statusBarChg = (CompanyStatusBarSelectList != oldAssignment.StatusBarID);
bool dspChg = (assignment.DSPID != oldAssignment.DSPID);

The only problem is that when I get to my Save(), I get this:
Attaching an entity of type [MODEL] failed because another entity of the same type already has the same primary key value. This can happen when using the 'Attach' method or setting the state of an entity to 'Unchanged' or 'Modified' if any entities in the graph have conflicting key values. This may be because some entities are new and have not yet received database-generated key values. In this case use the 'Add' method or the 'Added' entity state to track the graph and then set the state of non-new entities to 'Unchanged' or 'Modified' as appropriate.

Apparently, Entity Framework thought that my oldAssignment was blocking the assignment object from the postback.  The solution is simple: change this:

Assignment oldAssignment = db.Assignments.Find(assignment.UniqueID);

…to this:
Assignment oldAssignment = db.Assignments.AsNoTracking().Where(d => d.UniqueID == assignment.UniqueID).FirstOrDefault();

The .AsNoTracking() makes it so the oldAssignment loads the old values without telling Entity Framework that it owns the record in the table.

Tuesday, March 1, 2016

MVC: Splitting a list without splitting the dataset

Today I needed to split a list of companies into Companies and Relocation Companies.  The data is in the same table and model, but presentation rules for this project require 2 lists.

SO:

Taking a single dataset from the controller:

        // GET: Companies
        public ActionResult Index()
        {
            return View(db.Companies.ToList());
        }

I took this bit of view/index code from the auto-generated “Code First From Database” tool…

<h3>Companies</h3>
<table class="table">
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.CompanyName)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.isActive)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.isReloCompany)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.ChangedBy)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.LastChangedDate)
        </th>
        <th></th>
    </tr>

    @foreach (var item in Model)
    {
        <tr>
            <td>
                @Html.DisplayFor(modelItem => item.CompanyName)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.isActive)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.isReloCompany)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.ChangedBy)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.LastChangedDate)
            </td>
            <td>
                @Html.ActionLink("Edit", "Edit", new { id = item.UniqueId }) |
                @Html.ActionLink("Details", "Details", new { id = item.UniqueId })
            </td>
        </tr>
    }

</table>

And I made 2 copies (in my case I will only ever need 2 lists).  I changed the highlighted line in the above to…

    @foreach (var item in Model.Where(d => d.isReloCompany == false).OrderBy(d=>d.CompanyName))

Note that I can add LINQ into the view easily and I did not have to split my list beforehand in the controller.  The second copy of this line has .isReloCompany==true.